This competitive renewal proposes to study the effect of surgical intervention to improve the natural history of degenerative rotator cuff tears by comparing disease progression risks following surgery to the defined risks of asymptomatic cuff tears we have established with longitudinal studies. Additionally, we will also focus on defining risk factors upon presentation of a painful cuff tear that may predict future symptomatic development in the contralateral shoulder. This renewal will better define the potential benefit of early surgical intervention. IIA) Specific Aim 1: To obtain long-term follow-up (minimum 8 years) of a cohort of asymptomatic rotator cuff tears in subjects aged 65 years or younger to define the risks of tear enlargement and factors related to pain development. The most clinically relevant subjects within our cohort are those that retain good potential for tendon healing with surgical intervention. Further monitoring of these subjects is needed to define the long-term risks of non-operative treatment. The debate for operative indications is most relevant for patients that retain good healing potential with surgery and cannot be answered with only 5 years follow-up. The risks of tear deterioration without surgery must be determined through a period of time until healing is not likely because of patient age. IIB) Specific Aim 2: To assess the ability of rotator cuff repair surgery to interrupt the natural progression of degenerative cuff disease. The ability of surgery to halt the natural progression of degenerative rotator cuff disease has not been characterized. Untreated full-thickness rotator cuff tears enlarge in 50% of subjects, short-term. Tear enlargement is associated with declining function and advancing muscle degeneration. The natural history for non-operatively treated rotator cuff tears is concerning, in the short-term for disease progression. Because younger age and smaller tear size have been established as good predictors of healing with surgery, many advocate early repair in this group. These potential benefits are only realized if the natural history for repaired tendons is superior. Prospectively defining the benefits of surgery in subjects with good healing potential compared to nonoperatively treated tears will better define the role of early surgery. IIC) Specific Aim 3: o determine factors predictive of contralateral symptomatic rotator cuff disease progression based on the clinical presentation of a symptomatic rotator cuff tear. Approximately 56% of subjects with a painful rotator cuff tear will have an asymptomatic tear in the contralateral shoulder. Analysis of features related to the painful shoulder that may be predictive of future pain in the asymptomatic shoulder has not been previously considered. The ability to define patient and tear-related factors in the painful shoulder that are predictive of disease progression in the asymptomatic side will identify higher risk patients. Defining these factors is fundamental for counseling patients with degenerative rotator cuff tears and provides a foundation for patient education and implementation of preventive treatment strategies.